Puragra (Raja) GuhaThakurta
UCO/Lick Observatory
Department of Astronomy & Astrophysics
University of California Santa Cruz
271 Interdisciplinary Sciences Building
1156 High Street
Santa Cruz, CA 95064
Phone: (831)459-5169
FAX: (831)426-3115
Email: raja@ucolick.org
Science Internship Program (SIP):
Research opportunities in STEM fields at UCSC for high-school students
Click
here for the old SIP website.
Media coverage
February 2019:
All Space Considered
at Griffith Observatory, Los Angeles, CA
October 2018:
UCSC news article
about SIP interns placing among top high school presenters at the Sigma Xi Student Research Conference
October 2018:
Interview about STEM careers for STEM-Away featuring my graduate student Emily Cunningham and myself:
Emily's interview highlights,
Emily's full interview,
my interview highlights, and
my full interview.
April 2018:
Article in The Modesto Bee
about Modesto Area Partners in Science (MAPS) presentation
March 2018: TEDx talk "The Future of STEM Education"
The Nueva School, San Mateo, CA
January 2018:
Article in The PIE News
about the Global SPHERE Network
November 2017:
UCSC press release
about the launch of the Global SPHERE Network
November 2017: Article by Mark Mancini about galaxy morphology in
How Stuff Works:
"Why Galaxies Come in Different Shapes"
November 2017:
Article and video
about the W. M. Keck Observatory open house
September 2017: Op-ed piece in the Asian Age by Devi Kar:
"A bridge to link high school and varsity helps"
March 2017: Scientific consultant and subject matter expert for
fact sheet about the Andromeda galaxy
for the popular video game Mass Effect Andromeda
January 2017: UCSC press release "Science Internship Program creates opportunities for high school students"
April 2016: Talk "The Universe of Galaxies and STEM Research Opportunities for Young People" for
a group of Hawaii- and California-based high school students
(W. M. Keck Observatory HQ, Waimea, HI; videography: Liz Chock and Steve Jefferson)
February 2016: Article "Sky above, earth below and everything in between" by Devi Kar in The Telegraph (Kolkata, India)
October 2015: TEDx talk "The Importance of Engaging Youth in
Research: An Astronomer's Perspective" Harker School, San Jose, CA
January 2015: Press releases: Andromeda's disturbed stellar disk
(UCSC story and
(W M Keck Obs story) and the largest-ever Hubble image
(NASA story and a
high-resolution
movie clip with narration — best to download movie since it's probably too large for most
browsers to handle)
December 2014: Article "Sky's the limit for these
girls" about UCSC researchers mentoring high-school students in Kolkata, India (published in Telegraph, India)
September 2014: Article "Star
Studies" about the Science Internship Program by 2012/2013 intern Zareen Choudhury (published in "Imagine", a JHU/CTY magazine for
students)
July 2014: Article "High-school
scientists/Galactic exploration" (courtesy of International Innovation, Research Media Ltd. - a
leading scientific dissemination service) about the Science Internship Program and the SPLASH collaboration's research highlights
July 2014: Article in the Palo Alto Weekly entitled
"Stoking a passion for science" featuring the Science Internship Program
December 2013: Article
"Getting Girls to Thrive in STEM" in Castilleja School's Full Circle magazine
May 2012:
Press release
about the impending Andromeda-Milky Way collision
December 2011:
Google Tech Talk at Google HQ in Mountain
View, CA about "Our Place in the Cosmos"
July 2011:
Article
in Science magazine featuring the SPLASH group's work
January 2010: Press release on Andromeda tidal
streams:
UCSC site,
Keck Observatory site,
National Science Foundation site, and
Subaru Telescope site
SPLASH project collaboration page
Personal profile (summary of past research interests, mugshot!)
A picture's worth a thousand words...... (older research results)
Interstellar Dust Cloud:
High latitude tenuous clouds of
interstellar dust, commonly referred to as "cirrus", reflect ambient
starlight. An optical B band image of one
such nebula, 1038+83, obtained with the KPNO Burrell Schmidt telescope. We
have dubbed it "The Witch" for obvious reasons.
Optical spectroscopy of cirrus clouds with the Lick 3-meter telescope and
KAST spectrograph reveals evidence of photoluminescence from hydrocarbons.
Dense Star Cluster:
The centers of dense globular clusters are
excellent laboratories for studying the effects of stellar interactions.
The central density of M15 is among the highest of Galactic globulars. An
HST WFPC2 image of the central 9"x9" of M15,
color coded to represent intensities in the U, B and V bands, shows that the
stellar density rises all the way in to radii less than 0.5" (0.03 pc).
The Great Spiral Galaxy in Andromeda:
The combination of the KPNO
Burrell Schmidt telescope and 2048 x 2048 CCDs makes large area surface
photometry possible. This system has been used to construct an I band mosaic
image of the Andromeda galaxy (M31) covering 4 deg x 3 deg. The
central 1
square degree of M31, despite being subsampled 3 x 3 pixels in this
display, shows striking dust lanes. The satellite galaxy M32 is to the
south, while NGC205 (truncated by the mosaic edge) is to the northwest. The
full mosaic of M31 is displayed with
22 x 22 pixel block averaging (left) and median filtering (right). The
latter is more efficient at removing foreground stars. Note the gradient in
the projected density of foreground stars--the Galactic plane is to the
north (up)--and the prominent warp in M31's disk.
Internal Kinematics of Distant Galaxies:
Internal kinematics of
faint blue field galaxies can be a valuable probe of their evolutionary
history. A z=0.34 field galaxy from
our Fabry-Perot study with the CTIO 4-meter telescope shows an O[III] emission
line whose width, FWHM = 520 km/s, is significantly broader than the
instrumental resolution (left). Further, a spatially resolved kinematical
map of this galaxy shows clear evidence for rotation.
.....but, if you prefer to read, here's a selection of papers:
Galaxies, big .....
Kim, Guhathakurta, van Gorkom, Jura & Knapp 1988, "HI Observations of
the Elliptical Galaxies NGC2974 and NGC5018", ApJ, 330, 684
Guhathakurta, van Gorkom, Kotanyi & Balkowski 1988, "A VLA HI Survey of
the Virgo Cluster Spirals. II. Rotation Curves", AJ, 96, 851
Guhathakurta, Bernstein, Raychaudhury, Haynes, Giovanelli, Herter & Vogt
1993, "The Near-Infrared Tully-Fisher Relation: A Preliminary Study of the
Coma and Abell 400 Clusters", PASP, 105, 1022
Bernstein, Guhathakurta, Raychaudhury, Giovanelli, Haynes, Herter & Vogt
1994, "Tests of the Tully-Fisher Relation. I. Scatter in Infrared Magnitude
versus 21cm Width", AJ, 107, 1962
Frei, Guhathakurta, Gunn & Tyson 1996, "A Catalog of Digital Images of 113
Nearby Galaxies", AJ, 111, 174
Raychaudhury, von Braun, Bernstein & Guhathakurta 1997, "Tests of the
Tully-Fisher Relation. II. Scatter Using Optical Rotation Curves", AJ, 113,
2046
Guhathakurta & Reitzel 1998, "Local Group Suburbia: Red Giants in M31's Outer
Spheroid and a Search for Stars in the Magellanic Stream", in Galactic Halos,
ed. Zaritsky (ASP Conf Ser, v136), 22
Reitzel, Guhathakurta & Gould 1998, "Isolating Red Giant Stars in M31's
Elusive Outer Spheroid", AJ, in press (Aug 98)
..... and small, .....
Weinberg, Szomoru, Guhathakurta & van Gorkom 1991, "On the Population of
HI Dwarf Galaxies", ApJL, 372, L13
Gould, Guhathakurta, Richstone & Flynn 1992, "Evidence for Dwarf Stars at
D~100kpc Near the Sextans Dwarf Spheroidal Galaxy", ApJ, 388, 345
Szomoru, Guhathakurta, van Gorkom, Knapen, Weinberg & Fruchter 1994,
"The Properties of an HI-Selected Galaxy Sample", AJ, 108, 491
....., distant, .....
Guhathakurta, Tyson & Majewski 1990, "A Redshift Limit for the Faint
Blue Galaxy Population from Deep U Band Imaging", ApJL, 357, L9
Bahcall, Guhathakurta & Schneider 1990, "What the Longest Exposures from
the Hubble Space Telescope Will Reveal", Science, 248, 178
Efstathiou, Bernstein, Katz, Tyson & Guhathakurta 1991, "The Clustering
of Faint Galaxies", ApJL, 380, L47
Guhathakurta 1991, "Redshift Constraints and Clustering of Faint
Galaxies", in The Early Observable Universe from Diffuse Backgrounds, eds.
Rocca-Volmerange et al. (Editions Frontieres), 155
Rix, Guhathakurta, Colless & Ing 1997, "Internal Kinematics of Distant Field
Galaxies. I. Emission Linewidths for a Complete Sample of Faint Blue Galaxies
at z~0.25", MNRAS, 285, 779
Guhathakurta & Ing 1998, "Evolution and Internal Kinematics of Faint Blue
Galaxies", in Highly Redshifted Radio Lines, eds. Carilli et al. (ASP Conf
Ser), in press
.....and disturbed
Hibbard, Guhathakurta, van Gorkom & Schweizer 1994, "Cold, Warm, and Hot
Gas in the Late-Stage Merger NGC7252", AJ, 107, 67
Tyson, Fischer, Guhathakurta, McIlroy, Wenk, Huchra, Macri, Neuschaefer,
Sarajedini, Glazebrook, Ratnatunga & Griffiths 1998, "Deep Optical Imaging of
the Bright Seyfert NGC5548: A Long, Very Low Surface Brightness Tail", AJ, in
press (July 98)
Dust in our Galaxy.....
Guhathakurta & Draine 1989, "Temperature Fluctuations in Interstellar
Grains. I. Computational Method and Evaporation of Small Grains", ApJ, 345,
230
Guhathakurta & Tyson 1989, "Optical Characteristics of Galactic 100
micron Cirrus", ApJ, 346, 773
Guhathakurta & Cutri 1994, "Optical Studies of High Latitude Dust", in
The First Symposium on the Infrared Cirrus and Diffuse Interstellar Clouds,
eds. Cutri & Latter (ASP Conf Ser, v58), 34
Szomoru & Guhathakurta 1998a, "Optical Spectroscopy of Galactic Cirrus
Clouds: Extended Red Emission in the Diffuse Interstellar Medium", ApJL, 494,
L93
Szomoru & Guhathakurta 1998b, "Extinction Curves, Distances, and Incident
Radiation of Cirrus Clouds", ApJ, in prep
.....and in others
Jura, Kim, Knapp & Guhathakurta 1987, "Interstellar Dust in Shapley-Ames
Elliptical Galaxies", ApJL, 312, L11
Knapp, Guhathakurta, Kim & Jura 1989, "IRAS Flux Densities for Early-Type
Galaxies", ApJS, 70, 329
Dark matter
Richstone, Gould, Guhathakurta & Flynn 1992, "Constraints on Baryonic
Dark Matter in the Galactic Halo and Local Group", ApJ, 388, 354
Guhathakurta 1991, "Gravitational Lensing by Galaxy Clusters", in
Clusters & Superclusters of Galaxies, eds. Colless et al. (NATO ASI,
Cambridge), 55
Fischer, Tyson, Bernstein & Guhathakurta 1994, "Detection of Lens
Candidates for the Double Quasar Q2345+007", ApJL, 431, L71
Guhathakurta 1995, "Faint Blue Galaxies and Gravitational Lensing by Clusters
of Galaxies", in Sixth Asian-Pacific Regional Meeting, J Astrophys Astron
Sup, 16, 119
HST studies of dense globular clusters
Guhathakurta, Yanny, Schneider & Bahcall 1992, "Globular Cluster
Photometry with HST. I. Description of the Method and Analysis of the Core of
47Tuc", AJ, 104, 1790
Yanny, Guhathakurta, Bahcall & Schneider 1994, "Globular Cluster
Photometry with HST. II. U, V, and I Measurements of M15", AJ, 107, 1745
Guhathakurta, Yanny, Bahcall & Schneider 1994, "Globular Cluster
Photometry with HST. III. Blue Stragglers & Variable Stars in the Core of
M3", AJ, 108, 1786
Yanny, Guhathakurta, Schneider & Bahcall 1994, "WFPC2 Observations of
the Globular Cluster M30", ApJL, 435, L59
Guhathakurta, Yanny, Schneider & Bahcall 1996, "HST WFPC2 Observations
of the Globular Cluster M15. V. The Central Density Cusp", AJ, 111, 267
Edmonds, Gilliland, Guhathakurta, Petro, Saha & Shara 1996, "Stellar
Variability in the Central Populations of 47 Tucanae from WF/PC Observations
with the Hubble Space Telescope. II. Binary Systems", ApJ, 468, 241
Guhathakurta, Yanny, Schneider & Bahcall 1996, "Hubble Space Telescope
Studies of the Dense Central Regions of Globular Clusters", in Dynamical
Evolution of Star Clusters, eds. Hut & Makino (Kluwer, Dordrecht), 19
Cohen, Guhathakurta, Yanny, Schneider & Bahcall 1997, "Globular Cluster
Photometry with HST. VI. WF/PC-I Observations of the Stellar Populations in
the Core of M13", AJ, 113, 669
Guhathakurta, Piotto & Vesperini 1998a, "Mass Functions & Stellar Populations
of Globular Clusters", in Highlights of Astronomy v11, ed. Andersen
(Kluwer Acad Pub), in press
Guhathakurta, Webster, Yanny, Schneider & Bahcall 1998b, "Globular Cluster
Photometry with HST. VII. Color Gradients and Blue Stragglers in the Central
Region of M30 (NGC7099) from WFPC2 Observations", AJ, in press (Sept 98)